Method for manufacture of truss core sandwich structures and related structures thereof

ABSTRACT

An embodiment provides a method of constructing a cellular structure having nodes therein comprising: providing at least one truss layer comprised of at least one truss unit, at least one of the truss units being comprised of truss members; providing at least one panel in mechanical communication with the at least one truss unit of the at least one truss layer, the mechanical communication defines contact regions wherein the at least one truss unit is coupled to the at least one panel; the nodes being defined as intersections existing among any of the truss members and the nodes also being defined by the contact regions; providing at least one node pin, the at least one node pin spanning between two desired the nodes; and diffusion bonding at least one of the truss layer to the at least one panel. The bonding includes: applying heat, and applying force that results in the truss layer and the panel that are being bonded to be pressed together, the node pins provide support for the structure so as to concentrate or transmit the applied force onto the contact regions.

RELATED APPLICATIONS

This application is a national stage filing of International ApplicationNo. PCT/US2003/027606, filed on Sep. 3, 2003, which claims benefit under35 U.S.C Section 119(e) from U.S. Provisional Application Ser. No.60/407,756, filed on Sep. 3, 2002, entitled “Method For Manufacture ofTitanium Truss Core Sandwich Structures and Related Structures Thereof,”the entire disclosures of which are hereby incorporated by referenceherein in their entirety.

US GOVERNMENT RIGHTS

This invention was made with United States Government support underGrant No. N00014-01-1-1051, awarded by the Defense Advanced ResearchProjects Agency/Office of Naval Research. The United States Governmenthas certain rights in the invention.

BACKGROUND OF TH INVENTION

The present invention relates to a periodic cellular structurefabricated using three dimensional array of truss or truss-like unitsthat can be used as a multifunctional lightweight structural core forstructural panels. More particularly, the present invention relates to amethod of manufacturing such a periodic cellular structure usingdiffusion bonding techniques resulting in either an array or series ofstacked arrays of three dimensional truss units and resultant structuresthereof.

There exists a need in the art for manufacturing methods for makingtopologically controlled cellular metals that are applicable to titaniumand titanium alloys. The present invention provides, among other things,a new process that utilizes a diffusion bonding approach to create trusscores for sandwich panels and other panel types from titanium andtitanium alloys and other materials for which diffusion bonding isfeasible.

BRIEF SUMMARY OF INVENTION

An embodiment provides a method of constructing a cellular structurehaving nodes therein comprising: providing at least one truss layercomprised of at least one truss unit, at least one of the truss unitsbeing comprised of truss members; providing at least one panel inmechanical communication with the at least one truss unit of the atleast one truss layer, the mechanical communication defines contactregions wherein the at least one truss unit is coupled to the at leastone panel; the nodes being defined as intersections existing among anyof the truss members and the nodes also being defined by the contactregions; providing at least one node pin, the at least one node pinspanning between two desired the nodes; and diffusion bonding at leastone of the truss layer to the at least one panel. The bonding includes:applying heat, and applying force that results in the truss layer andthe panel that are being bonded to be pressed together, the node pinsprovide support for the structure so as to concentrate or transmit theapplied force onto the contact regions.

An embodiment provides a method of constructing a cellular structurehaving nodes therein comprising: providing at least one intermediatemember; bending at least one of the intermediate member to form a trusslayer comprised of at least one truss unit, at least one of the trussunits being comprised of truss members; providing at least one panel inmechanical communication with the at least one truss unit of the atleast one truss layer, the mechanical communication defines contactregions wherein the at least one truss unit is coupled to the at leastone panel; the nodes being defined as intersections existing among anyof the truss members and the nodes also being defined by the contactregions; providing at least one node pin, the at least one node pinspanning between two desired the nodes; and diffusion bonding at leastone of the truss layer to the at least one panel. The bonding includes:applying heat, and applying force that results in the truss layer andthe panel that are being bonded to be pressed together, the node pinsprovide support for the structure so as to concentrate or transmit theapplied force onto the contact regions.

An embodiment provides method of constructing a cellular structurehaving nodes therein comprising: providing at least one intermediatemember; providing at least one panel; providing at least two node pins,the at least two node pins located between the intermediate member andthe panel; applying at least one level of force that results in: theintermediate layer to be at least one of bent, stretched, and/orotherwise deformed or combination thereof into a desired geometry inresponse to at least in part to the node pins to form at least one trusslayer, the at least one truss layer being in mechanical communicationwith the panel, the mechanical communication defines contact regionswherein the at least one truss unit is coupled to the at least onepanel; and diffusion bonding at least one of the truss layer to the atleast one panel. The bonding includes: applying the at least one levelof force that results in the truss layer and the panel that are beingbonded to be pressed together, the node pins provide support for thestructure so as to concentrate or transmit the applied force onto thecontact regions.

An embodiment provides a cellular structure having nodes thereincomprising: at least one truss layer comprised of at least one trussunit, at least one of the truss units being comprised of truss members;and at least one panel in mechanical communication with the at least onetruss unit of the at least one truss layer, the mechanical communicationdefines contact regions wherein the at least one truss unit is coupledto the at least one panel; and the nodes being defined as intersectionsexisting among any of the truss members and the nodes also being definedby the contact regions. The at least one of the truss layer is diffusionbonded to the at least one panel. The diffusion bonding comprises:providing at least one node pin, the at least one node pin spanningbetween desired the nodes, applying heat, and applying force thatresults in the truss layer and the panel that are being bonded to bepressed together, the node pins provide support for the structure so asto concentrate or transmit the applied force onto the contact regions.

BRIEF SUMMARY OF THE DRAWINGS

The foregoing and other objects, features and advantages of the presentinvention, as well as the invention itself, will be more fullyunderstood from the following description of preferred embodiments, whenread together with the accompanying drawings, in which:

FIG. 1 provides a photographic depiction of perforated sheet beforeconstruction into a three-dimensional array of pyramidal trusses.

FIG. 2 provides a photographic depiction of perforated sheet afterconstruction into a three-dimensional array of pyramidal trusses.

FIG. 3(A) provides a photographic depiction of square cross sectiontrusses diffusion bonded to a panel (e.g., face sheet) in a pyramidalpattern.

FIG. 3(B) provides a photographic depiction of one truss layer having aplurality of Kagome truss units or Kagome-like bilayer truss unitsbonded to a panel (e.g., face sheet).

FIG. 4(A) is a schematic illustration of an embodiment of the diffusionbonding process.

FIG. 4(B) is a schematic illustration of an embodiment of the diffusionbonding process.

FIGS. 5(A)-(B) are schematic illustrations of an embodiment wherein thecore comprises one truss layer having a plurality of Kagome orKagome-like bilayer truss units or alternatively two layers of unittruss layers having a plurality of truss units, respectively. At leastone or two panels are provided on opposite sides of the core.

FIG. 5(C) is a schematic illustration of an embodiment as similarlyshown in FIGS. 5(A)-(B), wherein side panels are provided for bonding tothe core.

FIG. 6 is a schematic illustration of an embodiment wherein the corecomprises one truss layer on either side of a panel there between. Atleast one or two panels provided on opposite sides of the core.

FIGS. 7(A)-(C) are schematic illustrations of an embodiment wherein thecore is unformed or incompletely formed at the outset of the procedureand is formed by the applied force transmitted by node pins into a3-dimensional array of truss units, after which the transmitted forcecauses bonding of the truss units to the panel.

FIGS. 8(A)-(F) are schematic illustrations of embodiments wherein thecore comprises one truss layer between panels (or alternatively a paneland a tool) wherein the truss layers are defined by tetrahedral trussunits, pyramidal truss units, kagome truss units, diamond weave layers,hollow truss layers, and egg-box layers, respectively.

FIG. 9(A) is a schematic illustration of one embodiment of the bendingtechnique used to form a tetrahedral or tetragonal periodic cellulartruss layer.

FIG. 9(B) an enlarged portion of FIG. 9(A) showing a resultant trussunit of the truss layer after bending the intermediate member.

FIG. 10 is schematic illustration of an embodiment wherein the corecomprises a plurality of truss layers alternating with a plurality ofinterior panels (or tooling members) there between, all of which issandwiched between two panels (or tooling members).

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a cellular structure that is fabricatedin part by diffusion bonding or any other method of bonding requiringthe mechanical support of a cellular structure. As an example, anembodiment includes a titanium alloy, e.g., Ti-6Al-4V, but it should beunderstood that all materials of titanium and titanium alloys or othermaterials or applications for which the diffusion bonding process isdesired may be applied. Turning to FIGS. 1-3, the process may includethe bending of an intermediate member 11 forming trusses of square,rectangular triangular, circular, tubular, or other cross sectionalshape. The structure member 11 may be a perforated, porous, mesh, oraperture sheet. The intermediate member 11 comprises an array ofintersecting structural elements. Similarly, the intermediate member 11may comprise a multiple array of intersecting structural elements thatare stacked, woven, or coupled upon one another. Moreover, for example,the pores or apertures may include circular, square, rectangular,parallelogram, hexagonal, triangular, ellipsoidal, pentagonal,octagonal, or combinations thereof or other desired shape. The structuremember 11 may be an array of first intersecting structural elementsstacked on a second array of intersecting structural elements as shownin PCT International Application No. PCT/US03/PCT/US03/16844, entitled“Method for Manufacture of Periodic Cellular Structure and ResultingPeriodic Cellular Structure,” filed on May 29, 2003 (of which is herebyincorporated by reference herein in its entirety). The first and secondintersecting structural elements may be an array of wires, ligaments, ortubes (of which may be solid or hollow). The structure member 11 orfabricated core 21 may be an array of braided or intersecting textilestructural elements as shown for example PCT International ApplicationNo. PCT/US01/17363, entitled “Multifunctional Periodic Cellular SolidsAnd The Method Of Making Thereof,” filed on May 29, 2001, andcorresponding U.S. application Ser. No. 10/296,728, filed Nov. 25, 2002(of which are hereby incorporated by reference herein in theirentirety).

Moreover, the structure member 11 or fabricated core 21 may be a trussor truss-like unit as shown for example in PCT International ApplicationNo. Application No. PCT/US02/17942, entitled “Multifunctional PeriodicCellular Solids and the Method of Making thereof,” filed on Jun. 6, 2002(of which is hereby incorporated by reference herein in its entirety);or in PCT International Application No. PCT/US03/PCT/US03/23043,entitled “Method For Manufacture of Cellular Materials and Structuresfor Blast and Impact Mitigation and Resulting Structure,” filed on Jul.23, 2003. (of which is hereby incorporated by reference herein in itsentirety).

As shown in FIG. 1, porous or aperture intermediate member 11 (oralternatively array of intersecting wires or tubes) provides apertures12. In an embodiment the open area was about 87%, but it should beappreciated that various ranges of desired open areas may beimplemented. The bending or other deformation of the intermediate member11 results in array of truss units of pyramidal, tetrahedral, or otherarrangement so as to provide a core. As shown in FIG. 2, theintermediate member 11 is bent to provide a plurality ofthree-dimensional truss units 22 that form a three-dimensional trusslayer 23. In an embodiment the core density relative to that of thesolid material was about 1.7%, but it should be appreciated that variousranges of desired core densities relative to the solid may beimplemented. The intersections of these individual truss units shall becalled nodes 24.

As will be discussed later, and generally shown in FIGS. 2-5, forexample, when the three-dimensional truss layer 23 is assembled, some ofthese nodes 24 may come into mechanical communication with nodes from anadjacent truss layer, the outside tooling administering the appliedforce F on a face panel. These are known as contact regions 33. Contactregions are also defined wherein on truss unit layer is coupled to ormechanical communication with another truss unit layer. It should beappreciated that if the intermediate member 11 is deformed so that thedesired contact regions 33 is not at an intersection of truss members22, then that contact point shall be considered a node for the purposesof this work. Nodes are therefore defined by the areas formed by thetruss units coupled to the panels or the legs or ligaments of the trussunits intersecting with other legs or ligaments of the same truss unitor other truss units. It should also be appreciated that mechanicalcommunication at contact regions 33 does not necessarily mean directcontact, but may permit, for example, bond-aiding interlayers or otherinterlayers as desired. A diffusion bonding method is used in whichtitanium alloy facesheets or panels 31 are placed on the top and bottomof the core structure 21 (as defined as a layer(s) of three-dimensionaltruss layer 23 or the like as well as other components added thereto ifdesired). Node pins 41 are supports for the core structure 21 to preventundesired deformation of the core structure 21 while under loading fromforce F and the temperature of the assembly 1. As well as supporting thecore structure 21, the node pins serve to concentrate or transmit theapplied force F onto the nodes 24. In this manner, node pins 24 may beused to support the core from unwanted deformation, or to concentrate ortransmit the applied force F, or both. It should be appreciated that insome cases, node pins may transmit or concentrate all or a portion ofthe applied force F to the nodes 24 by a form of mechanicalcommunication other than direct contact. This mechanical communicationmay include a series of node pins that together transmit the desiredforce or portion of the force to the node 41 or contact region 33 to bebonded. It should also be appreciated that node pins may be used whensimple support is desired, but it is not necessary to concentrate theapplied force F. For any of these purposes, the geometry, arrangement,and shape of the node pins may be manipulated as desired. If the nodepins are assembled and designed so as to concentrate or transmit all ora portion of the applied force F to the contact regions 33, then thecontact regions 33 shall be subjected to a node pressure N, which isdefined as the applied force F or the desired portion of applied force Fthat is transmitted to the contact points 33 divided by the sum of thearea of contact regions 33. The assembly is placed in a vacuum furnace(or other types of furnaces) and heated to various ranges, includingabout 200° C. to about 2000° C., about 2000° C. to about 3730° C., 400°C. to about 1500° C., about 650° C. to about 950° C., or about 100° C.to about 300° C. with a node pressure applied having various ranges,including ranges of about 0.01 MPa to about 1000 MPa, about 0.01 MPa toabout 500 MPa, about 1 MPa to about 100 MPa, or about 0.1 MPa to about100 MPa. It should be appreciated that the force F can be applied fromthe top or bottom as shown and/or from the sides (not shown) if sidepanels are desirable. It should also be appreciated that applied force Fmay be varied throughout the process if desired.

It should be appreciated that the level of heat (or temperature beingsubjected upon the components), node pressure and air/gas/ambientpressure (e.g., vacuum, controlled atmosphere, or uncontrolledatmosphere applied shall be determined according to a number ofvariables including, but not limited thereto, temperature and otherenvironmental requirements for the desired process, structure, andmaterials and component type (e.g., panels, truss units, truss layer,core or other necessary components).

Turning to FIG. 4(B) for example, it should be appreciated that multipleface panels are not required for this design. The applied force F may beapplied to a structure with a truss core layer as the outermost layer oftwo or more bonded layers of face panels or truss layers, and themechanical communication between the node pins 41 and the toolingapplying the force F sufficient to bond the layers of the structure 1.

It should be appreciated that the face panels need not be a solid sheet.Face panels may be perforated, porous, mesh, or aperture sheet, as wellas an array of first intersecting structural elements stacked on asecond array of intersecting structural elements as shown in PCTInternational Application No. PCT/US03/PCT/US03/16844, entitled “Methodfor Manufacture of Periodic Cellular Structure and Resulting PeriodicCellular Structure,” filed on May 29, 2003 (of which is herebyincorporated by reference herein in its entirety). It should also beappreciated that the intermediate panels used between core assembliesmay be of any of these structures as well.

The truss units comprise of a plurality of legs or ligaments 25. Thelegs may have a variety of shapes such as straight or curved and mayhave a variety of cross-sections. Examples of the resulting truss coresandwich structures 1 are shown in photographic depictions of FIGS.3(A)-(B).

In addition to the high mechanical performance of truss core sandwichstructures 1 and/or the cores 21, they lend themselves tomultifunctional concepts. Such multifunctional concepts include heattransfer according to the design criteria and function as shown in PCTInternational Application No. PCT/US01/22266, entitled “Heat ExchangeFoam,” filed on Jul. 16, 2001, and corresponding U.S. application Ser.No. 10/333,004, filed Jan. 14, 2003 (of which are hereby incorporated byreference herein in their entirety).

Another multifunctional concept includes battery or power storage cores,for example, according to the design criteria and concept as shown inPCT International Application No. PCT/US01/25158, entitled“Multifunctional Battery and Method of Making the Same,” filed on Aug.10, 2001, and corresponding U.S. application Ser. No. 10/110,368, filedJul. 22, 2002 (of which are hereby incorporated by reference herein intheir entirety).

There are numerous other functionalities, which can be added into orwith these structures 1 (or with these arrays of cellular housings)making them ideal candidates for “structure plus” multifunctionalmaterials. For example the present invention general structural materialmay be involved in architecture (for example: pillars, walls, shielding,foundations or floors for tall buildings or pillars, wall shieldingfloors, for regular buildings and houses), the civil engineering field(for example; road facilities such as noise resistant walls and crashbarriers, road paving materials, permanent and portable aircraft landingrunways, pipes, segment materials for tunnels, segment materials forunderwater tunnels, tube structural materials, main beams of bridges,bridge floors, girders, cross beams of bridges, girder walls, piers,bridge substructures, towers, dikes and dams, guide ways, railroads,ocean structures such as breakwaters and wharf protection for harborfacilities, floating piers/oil excavation or production platforms,airport structures such as runways) and the machine structure field(frame structures for carrying system, carrying pallets, frame structurefor robots, etc.), the automobile (the body, frame, doors, chassis, roofand floor, side beams, bumpers, etc.), the ship (main frame of the ship,body, deck, partition wall, wall, etc.), freight car (body, frame,floor, wall, etc.), aircraft (wing, main frame, body, floor, etc.),spacecraft (body, frame, floor, wall, etc.), the space station (the mainbody, floor, wall, etc.), the submarine (the body, frame, etc.), and isrelated to the structural material which requires extreme dynamicstrength.

Varying the cross section of the trusses units 22, their arrangement,the thickness of the face sheets 11, and the thickness of the core 21enables control of the strength of the truss core sandwich structures 1and/or the cores 21. Various embodiments use trusses of square crosssection constructed by the bending of perforated or aperture sheet orarray of intersecting truss members. By using triangular, circular,hexagonal, rectangular, tubular, (four-sided or any number of sides)etc. cross section structures, the macroscopic stiffness of thestructure can be varied because the shape factors of the different crosssection shapes behave very differently mechanically. Structure members11 of a perforated pattern may be used as well to further varyproperties of the truss core sandwich structures 1. Because the trusscore sandwich structures 1 (or truss layer(s) with other panel(s) orsheet(s)) contain considerable surface area and empty volume, additionalfunctionality can be readily integrated into the structures.

Accordingly, the present invention provides, but not limited thereto,embodiments whereby the creation of a titanium, titanium alloy, cellularmetal, ceramic, polymer, metal, metal alloy, semiconductor or compositesystems (i.e., at least one of the truss units, truss layer, and/orpanels) are fabricated by diffusion bonding or other type of bonding.

Moreover, fabrication by using diffusion bonding or other type ofbonding of at least one of the truss units, truss layer, and/or panelscomprise of a material of at least one of, but not limited thereto:Ti-6Al-4V, TiAl, TiAlV, Ti, CP (Commercially pure) Ti, Ti-3Al-2.5V,Ti-5Al-2.5 Sn, Ti-6211, Ti-6242, Ti-8Al-1Mo-1V, Ti-11, TIMETAL 1100, IMI230, IMI 417, IMI 679, IMI 685, IMI 829, IMI 834, Ti-5Al-6 Sn-2Zr-1Mo-0.1 Si, Ti-17, Ti-6246, Ti-6Al-6V-2 Sn, Ti-7Al-4Mo, TIMETAL 62 S,SP-700, IM 367, IMI 550, IMI 551, Corona 5, Ti-6-22-22-S, Ti-4Al-3Mo-1V,Ti-5Al-1.5Fe-1.4Cr-1.2Mo, Ti-5Al-2.5Fe, Ti-5Al-5 Sn-2 Zr-2Mo-0.25 Si,Ti-6.4Al-1.2Fe, Ti-2Fe-2Cr-2Mo, Ti-8Mn, Beta III, Beta C, Ti-10-2-3,Ti-13V-11Cr-3Al, Ti-15-3, TIMETAL 21 S, Beta CEZ, Ti-8Mo-8V-2Fe-3Al,Ti-15Mo-5 Zr, Ti-15Mo-5 Zr-3Al, Transage 129, Transage 134, Transage175, Ti-8V-5Fe-1Al, Ti-16V-2.5Al, Ti-aluminides, Ti3Al alloys, GammaTiAl alloys, and/or TiNi smart metal alloys (SMA's).

Many core topologies can be created in this way. For example, titaniumalloy (or other diffusion bondable materials) can be made as a wire,ligament, leg, or tube.

Alternatively, rather than bending the structure members, it is possiblethat the truss layer or truss core is completely or partiallyprefabricated. An embodiment would require diffusion bonding variouslayers of the truss core together as well as diffusion bonding the trusscore to the panels. Various methods of prefabrication are possible.Various examples of prefabricated cores are discussed in PCTInternational Application No. Application No. PCT/US02/17942, entitled“Multifunctional Periodic Cellular Solids and the Method of Makingthereof,” filed on Jun. 6, 2002 (of which is hereby incorporated byreference herein in its entirety), including the construction ofcellular solids, which involves selective bonding of a solid or poroussheet within solid or porous sheets followed by internal expansion. Thiscould occur within the confines of a tool to produce near net shapeparts, the sheets have spot bonds prior to expansion.

Other methods are discussed in PCT International Application No.PCT/US03/PCT/US03/16844 (as cited above and is hereby incorporated byreference herein in its entirety) providing illustrations of embodimentsof the bending techniques used to form the stacked pyramidal periodiccellular structure.

FIG. 9 depicts one method of completing the bending step in order toachieve a desired truss layer 23. A wedge-shaped punch 7 is applied in adirection perpendicular to the planes of intermediate member 11 of thatis a perorated sheet comprised of elongated hexagonalperforations/apertures. As shown in FIG. 9, the wedge-shaped punch 7used to bend the intermediate member 11 into an interlocking die 8 suchthat the desired bending angles are achieved in the resulting trusslayer 23 comprised of tetragonal truss units 22. It should beappreciated that the wedge 8 and punch 7 may have a variety of bendingangles and sizes so as to achieve the truss units with appropriateangles and shapes. FIG. 9(B) is an enlarged portion of FIG. 9(A) showinga resultant truss unit 22 of the truss layer 23 after bending theintermediate member 11. Alternatively, a press, stamp, or rollingprocess (e.g., passage through a set of saw-toothed rollers or gears)may be used.

The examples shown in FIGS. 2-4 show the trusses arranged in a pyramidalpattern, and the aperture pattern necessary for the pyramidalarrangement. The pyramidal pattern and perforation pattern as shown arefor illustrative purposes only and therefore can be a wide variety ofshapes and sizes. For pyramidal cores, square, rectangular,parallelogram, or diamond perforations are effective. For tetrahedral,Kagome or Kagome-like cores, triangular or hexagonal holes are suitable.For example, turning to FIGS. 8(A)-(F), FIGS. 8(A)-(F) show schematicillustrations of embodiments wherein the core 21 comprises at least onetruss layer 23 between panels 31 (or alternatively may be a singularpanel or a tool) wherein the truss layers are defined by truss units 22that are tetrahedral truss units, pyramidal truss units, kagome trussunits, diamond weave layers, hollow truss layers, and egg-box layers,respectively. It should be further appreciated that the truss units asdiscussed throughout this document may be comprised of: legs orligaments; closed cell analogs (solid or semi-solid faces); or anycombination thereof.

In an embodiment, the diffusion bonding is achieved by applying a forceon the sheets 11 (or alternatively the core 21) that results in apressure of about 0.1 to about 100 MPa on the contacts areas 33 betweenthe panel 31 and the truss units 22 (or alternatively on the nodes 24between different truss layers 23). The nodes 24 provide a contact areaor region 33 for the applied force to produce a node pressure. Theassembly is placed into a vacuum furnace (or other type of furnace) andheated (if necessary) to about 650-950° C. As best shown in FIG. 4, nodepins 41 are used to support the truss units 22 and/or truss layers 23during the diffusion bonding process and to concentrate the appliedforce onto the panel 31 contact areas 33. In an embodiment, the nodepins 41 provide support for the core geometry and are aligned parallelor at least substantially parallel to the force being applied. The nodepins 41 concentrate or transmit the applied force onto desired contactregions 33 on the panel 31 and/or between truss layers 23 or nodes 24.These node pins 41 may be removed after the bonding process is completeor at a time when appropriate. Of course, the node pins may remain on alonger term basis if so desired, for whatever period of time may bedesired.

This sandwich structure 1 and/or core 21 can be readily varied such thatthe trusses layer(s) 23 may be used in any configuration. The overallmorphology, cell size, relative density, and mechanical behavior ofthese structures can be varied by the dimensions of the trusses, thecore thickness, the face sheet thickness, and the arrangement of thetrusses.

It should be appreciated that the panels 31 and/or cores 21 as discussedthroughout can be planar, substantially planar, and/or curved shape,with various contours as desired. The panels can be solid sheets,perforated or aperture sheet, mesh, or any other 2-D or 3-D panel.

It should further be appreciated that the truss units 22 as specificallyillustrated are designed to support axial loads, but are not limitedthereto. For instance, the truss units may also be designed so as tosupport bending moments as well.

Moreover, it should be appreciated that pyramid includes any four leggedor four sided truss unit (excluding bottom face) at various angles orside lengths. Similarly, tetragonal includes any three legged or threesided truss unit (excluding bottom face) at various angles or sidelengths. It should be appreciated that arrays of trusses with any numberof resultant leg arrangements may be produced and that production is notlimited to 3-legged or 4-legged structures.

FIGS. 5(A)-(B) are schematic illustrations of an embodiment wherein thecore 21 comprising two layers of unit truss layers 23 having a pluralityof truss units 22 or alternatively one truss layer 23 having a pluralityof Kagome truss units, Kagome-like truss, or bilayer units,respectively. While Kagome architecture is a certain arrangement, itshould be appreciated that Kagome includes Kagome structures as well asKagome-like structures. For instance, the truss may be any bilayer ortrilayer or higher, according to desired geometry. Turning to FIG. 5(A),for Kagome, Kagome-like truss units, or as desired geometry truss units,the node pins 41 generally span from node 24 to node 24 therebyextending from a panel 31 (i.e., at contact region 33 at orcommunication with panel) to other panel 31 (i.e., at contact region 33at or communication with panel) since the only bonding is at the contactregions 33 (as a result of the bilayer architecture as shown). Turningto FIG. 5(B), for an embodiment wherein the core 21 comprise two or morelayers of unit truss layers 23 the node pins 41 generally span from node24 to node 24 thereby extend from a panel 31 (i.e., at contact region 33at or communication with panel) to other panel 31 (i.e., at contactregion 33 at or communication with panel) as well as from node 41 tonode 41 wherein the truss layers 23 are coupled to one another at thecontact region 33 as a result of the truss unit layer on top being incontact with or communication with a lower truss unit layer as shown,for example. The use of these node pin arrangements are shown fortwo-layer cores, but are not limited thereto. The arrangement of nodepins may be extended to any desired number of layers of truss layers orface panels. The node pins keep the stress off the trusses, unless somedeformation of the truss members is desired. The core may settle ordeform slightly during bonding, but the node pins assure that thedesired geometry is achieved. It should be appreciated that any numberof truss layers and panels may be stacked upon one another. Further, thenode pins may not necessarily be used in all areas throughout thestructure, but rather as required or desired.

FIG. 5(C) is a schematic illustration of an embodiment wherein the core21 comprising two layers of unit truss layers 23 having a plurality oftruss units 22 or alternatively one truss layer 23 having a plurality ofKagome truss units, Kagome-like truss, or bilayer units. It should beappreciated that the node pins 41 may also extend horizonatally inresponse to side panels 34 being pressed onto the core 21 in response toforce F. It should be appreciated that the panels can have a variety ofshapes and sizes and applied to the core from a variety of directions(e.g., diagonally or as needed) other than directions specificallyillustrated. The node pins keep the stress off the trusses, unless somedeformation of the truss members is desired. The core may settle ordeform slightly during bonding, but the node pins assure that thedesired geometry is achieved. It should be appreciated that any numberof truss layers and panels may be stacked upon one another. Further, thenode pins may not necessarily be used in all areas throughout thestructure, but rather as required or desired.

FIG. 6 is schematic illustration of an embodiment wherein the core 21comprises one truss layer 23 on either side of an interior panel 32there between. The node pins generally span from node 24 to node 24thereby extending from the interior panel at the contact region 33 tothe exterior panel at the contact regions 33. The node pins keep thestress off the trusses, unless some deformation of the truss members isdesired. The core may settle or deform slightly during bonding, but thenode pins assure that the desired geometry is achieved. It should beappreciated that any number of truss layers, interior panels, andexterior panels may be stacked upon one another, as well as in betweenone another. Further, the node pins may not necessarily be used in allareas throughout the structure, but rather as required or desired.

FIG. 10 is schematic illustration of an embodiment wherein the core 21comprises a plurality of truss layers 23 alternating with a plurality ofinterior panels 32 there between, all of which are sandwich between twopanels (e.g., face sheets) 31. The truss layers 23 are comprised oftetragonal truss units 22 and the internal panels areperforated/aperture hexagonal sheets. It should be appreciated that oneor more of the exterior panels 31 and/or interior panels 32 may betooling members.

The truss units and truss layers may deform under heat and applied forcebut the node pins are there to assure a desired geometry. Therefore, thecellular structure could be laid up with the core incompletely deformedand the nodal pins finish the job of forming the core under appliedforce as well as supporting the core during bonding.

FIGS. 7(A)-(C) are schematic illustrations of an embodiment wherein thecore 21 is unformed or incompletely formed before application of appliedforce F. As shown in FIG. 7(A), the node pins 41 are placed so as to bein mechanical communication with the upper face panel 31 or the toolingexerting force F upon the assembly. As shown in FIG. 7(C), the node pins41 are placed so as to bend, stretch, or otherwise deform the unformedor incompletely formed core into a final geometry, and then undercontinued application of force F, bond the core truss layer 23 atcontact areas 33. FIG. 7(B) represents the core in a partially formedposition. It should be appreciated that F is not a fixed value duringthe forming and bonding steps and can be varied at different steps ofthe process as desired. Moreover, it should also be appreciated that thecore truss layer 23 may be of any geometry or arrangement. It should beappreciated that any number of truss layers, interior panels, andexterior panels may be stacked upon one another, as well as in betweenone another, as in the geometries and arrangements of any and allmultilayer assemblies shown above. Further, the node pins may notnecessarily be used in all areas throughout the structure, but rather asrequired or desired. Further, the node pins may be replaced or changedat various occasions during the process so as to further modify geometryor other procedural variables as required or desired.

The node pins 41 may be a variety of shapes. As shown in the drawingsthroughout this document, the node pins may be wider in a left to rightdirection and may be a variety of lengths extending through the plane ofthe paper as drawn. It should be appreciated that node pins may be ofany geometry desired in order to concentrate or transmit the appliedforce to the contact regions or to deform the material, or bothfunctions.

Intermediate 11 members of a perforated or textile pattern may be usedas well. There are a wide variety of processing variables that may bevaried to produce structures with unique properties.

At least some of the embodiments of the present invention provide, amongother things, a diffusion bonding process that enables the manufactureof periodic cellular cores with truss or metal textile core topologies.It requires no use of transient liquid phases, but other bonding methodsthan diffusion bonding, including those using transient liquid phases orother metallurgical bonding techniques, as well as including adhesivetechniques, may be used while using node pins for support. The processesof some of the various embodiments of the present invention processallows the strength of the structure to be high because the nodes formedby the contacts of the structure are of the same strength as the metalfrom which they are formed, as well as avoiding corrosive effects from abase metal in contact with a dissimilar filler metal. In addition, thesematerials lend themselves to multifunctional integration for heattransfer, power storage, energy absorption, and etc. applications. Also,this manufacturing technique of the various embodiments should beeconomically viable when compared with other periodic cellular metalsmanufacturing technologies.

The following publications, patents, patent applications are herebyincorporated by reference herein in their entirety:

-   -   1. U.S. Pat. No. 3,533,153 to Melill et al.    -   2. U.S. Pat. No. 3,633,267 to Deminet et al.    -   3. U.S. Pat. No. 3,981,429 to Parker    -   4. U.S. Pat. No. 4,043,498 to Conn, Jr.    -   5. U.S. Pat. No. 4,522,859 to Blair    -   6. U.S. Pat. No. 4,869,421 to Norris et al.    -   7. U.S. Pat. No. 4,893,743 to Eylon et al.    -   8. U.S. Pat. No. 5,024,369 to Froes et al.    -   9. European Patent No. EP 1 238 741 A1 to Leholm

Of course it should be understood that a wide range of changes andmodifications could be made to the preferred and alternate embodimentsdescribed above. It is therefore intended that the foregoing detaileddescription be understood that it is the following claims, including allequivalents, which are intended to define the scope of this invention.

1. A method of constructing a cellular structure having nodes thereincomprising: providing at least one truss layer comprised of at least onetruss unit, at least one of said truss units being comprised of trussmembers; providing at least one panel in mechanical communication withsaid at least one truss unit of said at least one truss layer, saidmechanical communication defines contact regions wherein said at leastone truss unit is coupled to said at least one panel; said nodes beingdefined as intersections existing among any of said truss members andsaid nodes also being defined by said contact regions; providing atleast one node pin, said at least one node pin spanning between twodesired said nodes; and diffusion bonding at least one of said trusslayer to said at least one panel, said bonding includes: applying heat,and applying force that results in said truss layer and said panel thatare being bonded to be pressed together, said node pins provide supportfor the structure so as to concentrate or transmit the applied forceonto said contact regions.
 2. The method of claim 1, wherein the appliedforce onto said contact regions provides a node pressure, said nodepressure being said applied force or portion of said applied forcetransmitted or concentrated upon said contact regions divided by the sumof the area of said contact regions.
 3. The method of claim 1, furthercomprising removing at least one of said node pins.
 4. The method ofclaim 1, further comprising providing at least a second panel inmechanical communication with said at least one truss layer distal fromsaid initially provided panel.
 5. The method of claim 1, furthercomprising providing at least a second truss layer in mechanicalcommunication with said at least one truss layer, said mechanicalcommunication defines contact regions wherein said at least one trussunit is coupled to said at least second truss layer.
 6. The method ofclaim 5, further comprising providing at least a second panel inmechanical communication with said second truss layer distal from saidinitially provided panel.
 7. The method of claim 5, further comprisingproviding at least a second panel in mechanical communication betweensaid first truss layer and said second truss layer.
 8. The method ofclaim 1, wherein said at least one truss layer and said at least onepanel comprise at least one select material, wherein said selectmaterial comprise: titanium or titanium alloy or any combinationthereof.
 9. The method of claim 1, wherein said at least one truss layerand said at least one panel comprise at least one select material,wherein said select material comprise: at least one of: Ti-6Al-4V, TiAl,TiAlV, Ti, CP (Commercially pure) Ti, Ti-3Al-2.5V, Ti-5Al-2.5 Sn,Ti-6211, Ti-6242, Ti-8Al-1Mo-1V, Ti-11, TIMETAL 1100, IMI 230, IMI 417,IMI 679, IMI 685, IMI 829, IMI 834, Ti-5Al-6 Sn-2 Zr-1Mo-0.1 Si, Ti-17,Ti-6246, Ti-6Al-6V-2 Sn, Ti-7Al-4Mo, TIMETAL 62 S, SP-700, IMI 367, IMI550, IMI 551, Corona 5, Ti-6-22-22-S, Ti-4Al-3Mo-1V,Ti-5Al-1.5Fe-1.4Cr-1.2Mo, Ti-5Al-2.5Fe, Ti-5Al-5 Sn-2 Zr-2Mo-0.25 Si,Ti-6.4Al-1.2Fe, Ti-2Fe-2Cr-2Mo, Ti-8Mn, Beta III, Beta C, Ti-10-2-3,Ti-13V-11Cr-3Al, Ti-15-3, TIMETAL 21 S, Beta CEZ, Ti-8Mo-8V-2Fe-3Al,Ti-15Mo-5 Zr, Ti-15Mo-5 Zr-3Al, Transage 129, Transage 134, Transage175, Ti-8V-5Fe-1Al, Ti-16V-2.5Al, Ti-aluminides, Ti3Al alloys, GammaTiAl alloys, and/or TiNi smart metal alloys (SMA's).
 10. The method ofclaim 1, wherein said at least one truss layer and said at least onepanel comprise at least one select material, wherein said selectmaterial comprise: ceramic, polymer, metal, metal alloy, and/orsemiconductor or any combination or composites thereof.
 11. The methodof claim 1, wherein said heat provides a temperature environment in therange of about 2000° C. to about 3730° C.
 12. The method of claim 1,wherein said heat provides a temperature environment in the range ofabout 200° C. to about 2000° C.
 13. The method of claim 1, wherein saidheat provides a temperature environment in the range of about 400° C. toabout 1500° C.
 14. The method of claim 1, wherein said heat provides atemperature environment in the range of about 650° C. to about 950° C.15. The method of claim 1, wherein said heat provides a temperatureenvironment in the range of about 100° C. to about 300° C.
 16. Themethod of claim 1, wherein the applied node pressure is in the range ofabout 0.01 MPa to about 1000 MPa.
 17. The method of claim 1, wherein theapplied node pressure is in the range of about 0.01 MPa to about 500MPa.
 18. The method of claim 1, wherein the applied node pressure is inthe range of about 1 MPa to about 100 MPa.
 19. The method of claim 1,wherein the applied node pressure is in the range of about 0.1 MPa toabout 100 MPa.
 20. The method of claim 1, wherein at least one of saidtruss units have units have a geometrical shape of at least one of:tetrahedral, pyramidal, Kagome, cone, frustum, or combinations thereofand other non-limiting arrangements.
 21. The method of claim 1, whereinat least one of said truss units have leg members.
 22. The method ofclaim 21, wherein at least one of said leg members is hollow or solid orcombination thereof.
 23. A method of constructing a cellular structurehaving nodes therein comprising: providing at least one intermediatemember; bending at least one of said intermediate member to form a trusslayer comprised of at least one truss unit, at least one of said trussunits being comprised of truss members; providing at least one panel inmechanical communication with said at least one truss unit of said atleast one truss layer, said mechanical communication defines contactregions wherein said at least one truss unit is coupled to said at leastone panel; said nodes being defined as intersections existing among anyof said truss members and said nodes also being defined by said contactregions; providing at least one node pin, said at least one node pinspanning between two desired said nodes; and diffusion bonding at leastone of said truss layer to said at least one panel, said bondingincludes: applying heat, and applying force that results in said trusslayer and said panel that are being bonded to be pressed together, saidnode pins provide support for the structure so as to concentrate ortransmit the applied force onto said contact regions.
 24. The method ofclaim 23, wherein the applied force onto said contact regions provides anode pressure, said node pressure being said applied force or portion ofsaid applied force transmitted or concentrated upon said contact regionsdivided by the sum of the area of said contact regions.
 25. The methodof claim 23, wherein at least one of said intermediate member comprisesa porous, mesh, or aperture sheet.
 26. The method of claim 25, whereinsaid pores or apertures of said intermediate member including acircular, square, rectangular, hexagonal, triangular, ellipsoidal,pentagonal, octagonal, or combinations thereof or other desired shape.27. The method of claim 25, wherein said pores or apertures are square,rectangular, parallelogram, or four sided shape whereby said bentintermediate member provides said array of said truss units whereby saidtruss units have a pyramidal shape.
 28. The method of claim 25, whereinsaid pores or apertures are hexagonal whereby said bent prefabricatedlayer provides said array of said truss units whereby said truss unitshave a tetrahedral shape.
 29. The method of claim 23, wherein at leastone of said intermediate member comprises an array of intersectingstructural elements.
 30. The method of claim 23, wherein saidintermediate member further comprises a second array of intersectingstructural elements stacked on top of said first array of intersectingstructural elements.
 31. The method of claim 23, wherein saidintermediate member further comprises a second array of intersectingstructural elements coupled to said first array of intersectingstructural elements.
 32. The method of claim 23, wherein at least one ofsaid structure member comprises an array of braided textile structuralelements.
 33. The method of claim 23, wherein at least one of saidstructure member comprises an array of intersecting textile structuralelements.
 34. A method of constructing a cellular structure having nodestherein comprising: providing at least one intermediate member;providing at least one panel; providing at least two node pins, said atleast two node pins located between said intermediate member and saidpanel; applying at least one level of force that results in: saidintermediate layer to be at least one of bent, stretched, and/orotherwise deformed or combination thereof into a desired geometry inresponse to at least in part to said node pins to form at least onetruss layer, said at least one truss layer being in mechanicalcommunication with said panel, said mechanical communication definescontact regions wherein said at least one truss unit is coupled to saidat least one panel; and diffusion bonding at least one of said trusslayer to said at least one panel, said bonding includes: applying saidat least one level of force that results in said truss layer and saidpanel that are being bonded to be pressed together, said node pinsprovide support for the structure so as to concentrate or transmit theapplied force onto said contact regions.
 35. The method of claim 34,wherein said at least one level of applied force onto said contactregions provides a node pressure, said node pressure being said appliedforce or portion of said applied force transmitted or concentrated uponsaid contact regions divided by the sum of the area of said contactregions.
 36. The method of claim 34, wherein said force for bending,stretching, or otherwise deforming is applied at least partiallysimultaneously during said force for bonding.
 37. The method of claim34, wherein said force for bending, stretching, or otherwise deformingis applied prior to said force for bonding.
 38. The method of claim 34,wherein said force for bending, stretching, or otherwise deforming isapplied partially after said force for bonding.